package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.*;
import static com.hmdp.utils.SystemConstants.CACHE_SHOP_KEY;


@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;
    @Override
    public Result queryById(Long id) {

        //缓存穿透
        //Shop shop = queryWithPassThrough(id);
//        Shop shop = cacheClient.queryWithPassThrough(
//                RedisConstants.CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
        Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
//        Shop shop = queryWithLogicalExpire(id);
//        Shop shop = cacheClient.queryWithLogicalExpire(
//                CACHE_SHOP_KEY, id, Shop.class, this::getById, 20L, TimeUnit.SECONDS);
        if (shop == null){
            return Result.fail("店铺不存在");
        }
        //7.返回信息
        return Result.ok(shop);
    }

    //创建线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    //逻辑过期解决缓存击穿
    public Shop queryWithLogicalExpire(Long id){
        //1.从redis查询商铺缓存
        String Key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(Key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)){
            //3.不存在，直接返回
            return null;
        }
        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //5.1.未过期，直接返回店铺信息
            return shop;
        }

        //5.2.过期，需要缓存重建
        //6.缓存重建
        //6.1.获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2.判断是否获取锁成功
        if (isLock){
            //6.3.成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                //重建缓存
                try {
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }


        //6.4.返回过期的商铺信息
        return shop;
    }

    //互斥锁解决缓存击穿
    public Shop queryWithMutex(Long id){
        //1.从redis查询商铺缓存
        String Key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(Key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)){
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if (shopJson != null){
            return null;
        }
        //4.实现缓存重建
        //4.1.获取互斥锁
        String lockKey = "lock:shop:" + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2.判断是否获取成功
            if (!isLock){
                //4.3.失败，休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }


            //4.4.成功，根据id查询数据库
            shop = getById(id);
            //5.模拟重建的延时
            Thread.sleep(200);
            //5.不存在，返回错误
            if (shop == null){
                stringRedisTemplate.opsForValue().set(Key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(Key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //7.释放互斥锁
            unlock(lockKey);
        }
        //8.返回
        return shop;
    }

    //封装缓存
    public Shop queryWithPassThrough(Long id){
        //1.从redis查询商铺缓存
        String Key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(Key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)){
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if (shopJson != null){
            return null;
        }
        //4.不存在，从数据库查询，再保存到redis
        Shop shop = getById(id);
        if (shop == null){
            stringRedisTemplate.opsForValue().set(Key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //6.存在，写入redis
        stringRedisTemplate.opsForValue().set(Key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回信息
        return shop;
    }

    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //写入redis
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }

    //创建互斥锁
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key,"1",10,TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    //删除互斥锁
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    @Override
    @Transactional  //事务回滚
    public Result uodate(Shop shop) {
        Long id = shop.getId();
        if (id == null){
            return Result.fail("店铺ID不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if (x == null || y == null){
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id",typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        // 3.查询redis，按照距离排序、分页 结果：shopId、distance
        String Key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()  // GEOSEARCH Key BYLONLAT x y BYRADIUS 10 WITHDISTANCE
                .search(Key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));
        // 4.解析出id
        if (results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from){
            // 没有下一页，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取from-end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);

        });
        String idStr = StrUtil.join(",", ids);
        // 5.根据id查询shop
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        // 6.返回
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }
}
